- the response, as affecting growth or reproduction, of an organism to the length of exposure to light in a 24-hour period.
Origin of photoperiodism
Also called pho·to·pe·ri·o·dic·i·ty [foh-toh-peer-ee-uh-dis-i-tee] /ˌfoʊ toʊˌpɪər i əˈdɪs ɪ ti/.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- the response of plants and animals by behaviour, growth, etc, to photoperiods
Word Origin and History for photoperiodism
Online Etymology Dictionary, © 2010 Douglas Harper
- The response of an organism to changes in its photoperiod, especially as indicated by vital processes.
- The response of an organism to changes in its photoperiod, especially as indicated by vital processes. For example, many plants exhibit photoperiodism by flowering only after being exposed to a set amount of daylight, as by requiring either a long or short day to flower. Plant growth, seed germination, and fruiting are also affected by day length. Photoperiodic responses in plants are regulated by special pigments known as phytochromes. In animals, migration, mating, amount of sleep, and other behaviors are also photoperiodic. In many animals, photoperiodism is regulated by the hormone melatonin.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.